In the building of sports stadiums and the like, there has been an ever increasing tendency to go to retractable roof designs allowing an outdoor feeling in good weather conditions and the closing of the roof in bad weather conditions.
The standard arrangement in a retractable roof is one which includes central roof sections which retract to provide a single central roof "overhead" opening.
Several problems result from the construction described immediately above. Firstly, during most times of the day, the sun is not in fact directly overhead and therefore the center roof opening does not maximize the effect of the sun. Furthermore in some cases, the shadows thrown by the position of the sun relative to the center opening creates severe problems for athletes playing within the building or stadium, and for T.V. monitoring.
A further problem encountered with the overhead type opening is that it is essentially stagnant and is not well exposed to air circulation. The only way for the outside air to enter the stadium is to come directly down through the opening. In fact, the opposite is more likely to be true where there tends to be a suction of air out of rather than into the stadium.
Still another problem with the overhead retractable roof is that it necessitates the handling of very large pieces of moving roof sections which are both awkward and expensive.